Self-propelled tractors are used for a variety of purposes in agriculture, for example cultivation, for spreading material such as seed or fertilizer on the field, for harvesting or for transport work. Accordingly, different implements, such as plows, seeders, fertilizer spreaders, balers, mowers, attached forage harvesters or transport trailers, must be coupled to the tractor. The tractors are therefore equipped with one or more interfaces at which different implements can be attached. Such interfaces can comprise a trailer hitch for towing a transport trailer or baler for example, a rear power lift (generally a three point hitch) at the rear end of the tractor and/or a front power lift (generally a three point hitch) at the front end of the tractor, each of which can be used for attaching implements not coupled by a tow bar, such as mowers, field sprayers, forage harvesters, fertilizer spreaders, seeders or plows. In addition to tractors, other types of self-propelled working vehicles are also used in agriculture, such as self-propelled harvesting machines (e.g., combine harvesters or forage harvesters) or vehicles for moving loads (e.g., an earthmover or telescopic handler).
A variety of arrangements for automatic control of travel speed and steering movements of agricultural working machines on the field have been described. For controlling the speed, these arrangements can be based on measurements of crop properties or tensile force measurements while cultivating, and for steering, these arrangements can be based on optical detection of a swath to be picked up or a travel lane or a map of the field in conjunction with a position determination by means of a satellite-based position detection systems. In certain prior art, however, specifying the speed and steering a working machine when driving on a road has been done manually by the driver of the working machine. This driving can be relatively fatiguing on extended working days and is difficult and dangerous with heavily loaded trailers or with large and heavy implements, especially for relatively inexperienced personnel.
A number of arrangements for automatic distance control are known from the automotive field, using sensors for recognizing the distance and speed of a preceding vehicle (German Patent Application No. DE 10 2013 013 243 A1) and/or communication of vehicles with one another (German Patent Application No. DE 40 35 501 A1). The loading of the vehicle, particularly a truck with or without a trailer or a passenger automobile with a trailer or a luggage carrier, which have an influence on the driving dynamics of the vehicle, is important for controlling the speed of the vehicle, and therefore it has already been proposed to have the data regarding the load input by the driver or automatically detected by sensors (German Patent Publications DE 10 2013 013 243 A1, DE 20 2011 100 493 U1, DE 20 2011 100 844 U1, and DE 10 2011 012 407 A1). The arrangement for specifying the travel speed of the vehicle thus obtains data regarding the trailer itself, such as the empty weight thereof, as well as data detected by sensors or manually input, and considers these for controlling the speed.
German Patent Application DE 10 2007 032 310 A1 describes a self-propelled working vehicle in which a monitoring device applies a variable force via an actuator to the speed input means (accelerator pedal) controlled by the driver, with the intention of inducing the driver to drive at an appropriate speed with regard to economy or safety aspects. Accordingly, if the driver attempts to drive faster than is appropriate, the accelerator pedal can only be moved downward against a relatively high resistance. For this purpose, the force acting on the working machine from a trailer or implement, or the yawing moment of a working machine when cornering, are detected by a sensor and compared to a threshold value.
Finally, it has been proposed to identify attached implements, based on identification plaques attached thereto on which machine-readable information for identifying the implement is present, by means of a camera and image processing software in order to be able to facilitate maintenance and repair work or to be able to make adjustments to the working machine (German Patent Application DE 10 2013 109 444 A1); physical properties of the working machine such as the position of the center of gravity, as well as operating parameters of the identified attached implement such as the PTO speed, are determined for this purpose (German Patent Application DE 10 2012 109 210 A1), and additional information can be downloaded based on a reference to an Internet address that is included in the identification plaque. Such information can also be provided in a storage element that is physically connected to the attached implement (German Patent Application DE 102 30 474 A1).